Method and apparatus for treating clay ware in tunnel kilns



March 24, 1925.

C. B. HARROF METHOD AND APPARATUS FOR TREATING CLAY WARE IN TUNNEL KILNS 2 Sheets-Sheet l- INVENTOR.

Filed July 6,

A TTORNEYS.

Marh 24, 1925.

C. B. HARROP METHOD AND APPARATUS FOR TREATING CLAY WARE IN TUNNEL KILNS ts-.Sheet i Patented Mar. 24, 1925. i

PATENT OFFICE.

cam. B. mtime?, or COLUMBUS, 01110.

METHOD AND APPARATUS. FOR TREATING CLAY WARE IN TUNNEL KILNS.

Application filed July 6, 1921. Serial No. 482,647.

I'o all web mn t1/lay concern.' l

Be it known that I, CARL B. Hnnnor, a citizen of the/United States of America, residing at Columbus, in the county of Frank` lin and State of Ohio, have invented certain` new and useful Improvements iirllflethods and Apparatus for'Treating Clay Ware 14 Tunnel Kilns, of which the following is a... specification. l y

My invention relates .to method and :1p-I` paratusjfor `treating eliiy ware 1n tunnel kilns and pertains'to what is commonly.f known as direct-fired continuous car tunnel kilns. It has to ido. particularly with the control of temperatures and circulation m a highly novel and effective manner whereb the heat gradient throughout the length of the kiln will be under better control and the temperatures of the ware .at all stages of firing will be more uniform throughout the cross-section ot the car setting. Hitherto the treatment of clay ware in this type of kiln Vhas largely consisted in passing the ware through a kiln into which heated gases are introduced and then left practically without scientific regulation as to method and degree of actual application.

My invention is vtounded in part upon a realization l-hauthc treatment and more particularly the tiring ot' the clay wares is a scientific problem and should be handled as such. More speeilically, l have conceived that the proper iriug of clay wares does not consist merely in creating a heated zone 1nd then passing the ware'to be tired -through such zone, but, that it -`is highly desirable in the heat treatment of some wares to maintain a nearly constant temperature at certain periods without'great rise or fall in suoli temperatures, while at other periods in the treatment a rapid gain or loss in temperature is desirable. Thus, I have provided a method and means which not only makes possible the variable regulation vof temperatures at different periods but which also makes'possible the regulation ot the lengths of such periods. Y

More specifically, my invention comprises, in part, the passing of the gases, while treating the ware, through restricted and free areas which may vary in size, aud location.

This is desir-ably attained by building the kiln in such a manner that relatively wide f and narrow passages for the gases are proy:vided at predeternnned sections of the kiln.

The result is that the gases passing through tite restricted zone or zones will travel with greater velocity than when passing through tte free zones. Thus in the restricted zones,

temperature readings of the gases throughout such zones will show little vari- Sauce, while in the free zones the lessened velocity of the gases will allow them to give V 1 up more of their heat because of their lower rate of travel with the result that the temperature readin s Will show a wide variance from end to en of these zones.

I have found that by the judicious use of I these restricted and free Zones, the tempera- Y ture gradient throughout the length of the kiln may be arranged to suit the material to be treated. Thus, it is desirable in the heat treatment of some wares to maintaina steady temperature at certain periods Without material rise or fall inthe same and for varying lengths of time, while at other periods in the treatment a rapid gain or loss in temperature is desirable.

Another phase of my invention has to do with the maintenance of balanced pressure conditions above and below the ear platf formsthroughout the length of the kiln and the ensuring ot' a proper circulation of air beneath the car platforms for cooling the vars. In acrordanee with this, I havel pro vided my kiln with a means whereby, whenever necessary, air may be withdrawn by the pressure fan from beneath the car platforms in zones where there is a negative pressure above the car platforms to ensure a similar negative pressure beneath such platforms. Likewise, in zones where there is a positive pressure above the car platforms as, for instance, at the discharge end of the kiln, I have provided means for injecting air into the space beneath such platforms to ensure` a balancing of the positive pressure above in such zones.

There are other features ofniy method and apparatus which will appear'as this description progresses. The preferred embodiment of my inventionlis shown in the accompanying drawings wherein similar characters of reference designate corresponding parts and wherein- Figure 1 is a vertical longitudinal section of my kiln structure. I

Figure 2 is a horizontal longitudinal section of the structure shown in F ignre'q.

Figure 3 is a transverse section taken on line 3-3 of Figure 2. g

Figure l is a detail in side elevation of the structure shown in Figure 3.

Figure v5r is a transversesection taken on line 4-4 of Figure 2.

Figure 6 is a transverse section taken on line 5 5 of Figure 2, illustrating a relatively slght clearance which will ensure a particularly high velocity of the gases along the kiln. t

Figure 7 is a transverse section taken on line 6-6 of Figure 2 showing a eater i clearance between the ware and the sldes of the kiln with a resultant lowering of the velocity of the gases, this figurel illustrating serrated `surfaces (which for convenience are indicated on one side only) to further amplify the absorption of the heat from the gases and subsequent increased heating of thepware by radiation from such serrated walls. v

Figure 8 is a detail showing the pressure gage tfrt Tdesirably utilize to indicate the pressure; 'conditions on opposite sides of the sand seals which separate the space beneath the car-platforms from the space above the car latforms'and the preferred manner of app ying such gage.

- In ythe drawings, I have-shown a tunnel kiln havin a Hoor 1 with tracks 2thereon upon Iwhicl are designed to run a series of cars that-may be designated 3.

These cars are provided with depending side flanges 4' which extend into the sand troughs as indicated at 5 in Figure 8 to form an air seal.1 The cars are further reduced upon their edges as at 6 so that they fit in' horizontal grooves 7 in the vertical walls 8 of the kiln structure.

The crown of the kiln may be designated 9 and is` provided with chambers 10 and 11 therein. The chamber 10 is provided at 12 with a port desirably directed away from the discharge end of the kiln but adjacent such discharge end. Air under pressure is introduced into -the kiln through the port 12 and passesin'to cooling contact with the ware a`nd ultimately reaches vthe furnace zone where it is utilized as secondary air for combustion. The chamber 11 extends along the crown of the kiln and subject to the heat thereof, being provided adjacent `one of its ends with downwardly extending delivery channels 13 and 14 leading to the several furnaces.

At one side of the kiln adjacent the ends of the chambers 10 and 11 is provided a pressure fan 15 with an u standing conduit 16 and with a downwar ly turned branch conduit 17. The upwardly extending conduit 16 is provided with a branch conduit 18 that delivers -lair under pressure into chamber 10 and is also provided With a branch 19 that delivers air under pressure into chamber 11, both branches 18and 19 being provided with blast gates for controlling the pressure and volume of air admitted to chambers 10 and 11. The downwardl extending branch conduit 17 passes to an delivers air under pressure into the kiln in the space beneath the car platforms at a point near the dischar e end of the kiln land near where the positi pressure inthe space above the car platforms is the greatest.

The pressure fan is likewise utilized as a vacuum fan by means of a conduit 20 extending into its side and connected at its opposite end beneath the car platforms at a point which is beneath :the zone of the greatest draft above the car platforms.

he degree of vacuum and pressure may be controlled at will by the use of blast gates 21 and by the use of air inlets or outlets 22 having valves at their outer ends. These inlets or outlets are in the form of coiiduits which extend through the base of the kiln and into the space beneath the cars. To facilitate the control of the positive and negative ressures, I have placed ai: dams 23 beneat the c ar platforms and near the discharg-l end of the kiln, as well as a dam 24 at t e approximate point in the kiln Y'above which in the main tunnel the pressure changes from positive to negative. In con- ]unction with these air ams, I.have provlded air dams 25 and 26 in spaced relation adjacent the. entrance end of the kiln.

These air dams serve to effectually restrict the area between the base of the kiln and the cars so that the pressure conditions inthe. space underneath the car platforms may be more'readily controlled and made to correspend more closely with the pressure conditions in the tunnel proper above thc car platforms. It willbe obvious that the pressure beneath the cars can be e'ectually controlled by opening or closing any fone or more of the inlets or outlets '22 andby properly regulating blast gates 21.'

By reference to Figures 1 and'2 it will be noted that I have provided a plurality of exhaust ports 27 which connect with the dra-ft ducts 28 that are in turn connected'to the exhaust fan 29. Y

It will also be noted that I have prt. 7ided a gage 30 with one pipe 31 leading there-- from to the space above the sand seal and with another pipe 32 leading therefrom to the space below the sand seal. A plurality f of these gages are to be inserted at frequent intervals within the length of the kiln and they will show at a glance the relative pressures above and below the cars. Whenever these pressures areffound -to be materially unequal, steps a're'to` be takento so adjust the pressure underneath the car platforms as to produce substantially balanced. pressures on the two sides of'the sand seals. Normally, these stepsconsist in withdrawing airv from the lower space underneath the car platform of the kiln when the pressure in this space is in excess of that in the upper space at any given location;. or, if the pressurel in the upper space is greater, suiicient air will be .introduced into the lower space immediately, therebeneath to cause a substantially balanced condition.

When the kiln is operated under normal conditions, there will be a condition of .positive pressure existing' inthe `=kiil'n above .the car platforms from adjacent the discharge end to a point near the fire zone. Approaching th'e fire zone, the sitive pressure will decrease and finally bcome negative pressure. This negative pressure condition will persist from the fire zone4 to the charging end of the kiln. lThe condition of positive pressure'at the discharge end 'of the kiln naturally results from the admission of air under' pressure at the delivery port. 12--of the chamber '10. The air traveling through the kiln toward the entrance end'coolsthe fired ware, then becomes secondary air for'eombustion in the furnace zone and, together `with the furnace gases, gives up heat to the incoming ware, being finally drawn out through the exhaust PrtS27 i J' By examination of Figures 5,6 and 7,-it

w'ill be apparent vthatvarying conditions of',l clearance will be produced at different zones in the kiln, the location of these zones. vary` ing somewhat withthe .difl'eifntfclassesvof ware'to be fired.

a consequent slight diop in the teinl'ieratiire of the gases throughout such paages and providing av decreased velocity at othe 'i-`l'"lo'.v cat-fons with a consequent increased absorpf.A tion of heat from the gases and a much and controlling the velocity ot' the ItI will be obvious thatt' thus becomes possible. to regig'ilate velocity of vthe 'heating gases throughout these [mssages along the kiln, providing .an increased velocity at certain locations with gasesto regulate the amount of heat imparted.to the kiln walls and to the ware at different. zones in the kiln.

2. The method of treating clay ware in :i Y 'tunnel kiln which comprises passing the ware through the kiln on ware carrying units which are so constructcdthat the spare above' the cars'will be sealed from the space below the car platforms, and maintaining substantially the same pressure both above and below the car platforms.

3. The method of treating clay ware in a tunnel kiln which comprises maintaining' at any given location substantially the same positive or negative ressure beneath the car platforms as exists a ove.

4. The method of treating clay ware in :i tunnel kiln; which comprises withdrawing air from beneath the car platforms in those locations where negative pressure exists above said platforms.

5. The method of treating clay ware in a tunnel kiln which comprises introducing air under pressure beneath the carplatforms in those locations where ressure exists above said platforms and withdrawingair from beneath the car platforms in those locations where negative pressure exists above said platforms.

6. The method of treating clay ware in tunnel kiln which comprises separating the space beneath the cars into one space which is substantially coincident with the pressure location above and into a second space which is substantially coincident with the negative pressure location above, and "regulating the air pressure in both spaces to produce a balanced pressure above and below.

7. vA tunnel kllnwhich is constructed internally with clearances between the ware setting and the kilnl walls of varying area at diifrsafglceations. tnnelkiln wherein the heatinofgascs direct contact with the ware wiich is ratedf'srface's tzllioscn locations to increase the heat absorbed-in such locations from the gases passing therethrough. l f -9.' tunnel kiln wherein the heating gases assin` direction contact with the ware com- -prisin'g irregularities in its interor wall surfacesv tofvary the heat absorbed from the gases and radiatedv to the ware.

10. A tunnel kiln wherein the heating gases pass in direct contact with the ware. 120 comprising serrations in its interior wall surfaces to increase the heat absorbed from the gases.

l1. A tunnel kiln comprising relatively large and small areas through which the Ware and the gases both serrated walls. 12. A tunnel kiln comprising means for delivering air under pressure to the space beneath the car platforms in the location 4130 pass and which havel Wherey positive pressure exists above said L, platforms. f

.13.A tunnel kiln comprising means for i delivering air under pressure to the space beneath the ear platforms in the location `where positive pressure exists above said platforms and a plurality of independent regulable inlets or outlets in such space.

y '14. A'tunnel. kiln comprising means for withdrawing air from. the space beneath the car platforms in the location Where negative i pressure exists above said platforms.

15. A tunnel kiln comprising means for `delivering air under pressure to the space beneath the car platforms in the location Awhere( positive pressure exists above said platforms and Ameans for withdrawing air from the space beneath thercar platforms in negative pressure exists above said platforms and means for substanti` lly separating such spaces from each other. 4 Y

17. A tunnel kiln comprising means for delivering air under ressure to the` space beneath .the car platfldrms inthe' location where positive pressure exists above said platforms, means for withdrawing air from the space beneath the car platforms Where negative pressure exists above said vplatforms, means for`substantially separating such spaces from eachv other and means for indicating relative pressure conditions at`various points above and below thecar platforms. l i

18. A tunnel kiln comprising `means for delivering air under pressure to the s ace beneath the car platforms ir' the zone w ere positive pressure exists above' said platforms, means for withdrawing air from ythe` space' beneath the-car platformsin the lzone 4where negative pressure .exists labove Asaid platforms and air dams for substantiallyvseparating said spaces.

In testimonywh'ereof I hereby affix-my signature.

CARL B. Hannon 

